For anyone skinny, building a narrow chair, you could still move the rear wheels 10mm inboard (each side) if required and then it will be under 25 inches total. I left the 10mm gap so I can later on bolt on 4.5 wide rims, and even lower profile 145 tyres. As soon as I can find a set this side of the Atlantic.

Which I needed on, because it lets me configure the battery in multiples of 8 to take the best advantage of the space available. This is ESSENTIAL to take full advantage of the lithium battery.

Max capacity I can fit (easily) is 120Ah. (80x 12cells). Because one of the great things about these headway cells, over the typical prismatic cells, (or lead) is that it can be configured to use up all of the available space. It need not be rectangular. Or even all in one place.

As you can see they all vary, and cell 6 varies more than I like. I ordered 2 extra cells. I may not use the 122mAh lost cell. This way I can assemble GROUP[S of cells that have the same AVERAGE self discharge. So they will stay in balance if unused for a while.

Well its hard work. Esp if you spend most of the time held up waiting for a carer to pick up that screw, tool, bracket, or whatever that you needed and you have been running over all day, or waiting for the post from china for some obscure tiny thing you cant do without...

I have a BM3 with a failed Cush drive rubber I need to fix, so cant use it. But cant fix it because I have a BM2L (lithium) in the way covering every spare bit of space in 200 bits and pieces.

Charge cable connected and testing. Just ONE connection. That black connector. One half stays on the chair, bolted under the seat. Other half stays on the charger. That connector has 9 balance wires, and 2 power wires. Safe for 40A charging.

It cant get any easier! The PL8 charger does a much better job of charging, with better control and information than a BMS. And the chairs controller does a better safer current and voltage control limiting than a BMS too. So non is required.

And apart from lasting a great many years, this battery is SAFE! Not all lithium batteries catch fire! These LiFePO4 cells are SAFER than your existing lead batteries.

Very nice! I wish I had known of those connectors before I did the Anderson and aviation plug connection to charge my 14s pack. It works fine but is three things to plug in. Simple enough but the aviation plugs are pretty annoying to get connected good.

What's the heavy red cable at the top for? The short one horse-shoe'd over. It looks to be making a parallel connection. I was wondering why it instead of a two hole plate?

The battery is in 2 halves. Hence the link cables. Tried Anderson, has too much resistance and at 40A charge cell 4 shows 10mV too high... So solid cable link. And very tight bus bars. It even matters where you connect the balance wires. Can be 5mv difference from one end of a bus bar to the other...

Get it right and it looks perfect and the exact same voltage to 3 decimal places on every cell.

If you fit the cheap turnigy watt meter, you can find out ultimate range easily. With lithium as you already know, there's no Peukert. They run at full power to 99 percent. So you can measure actual Ah used, over a typical day, use your phone GPS to measure miles, and just do the maths. It will be within 1 percent. Range should be rather good. Lower current 6.2mph motors. Rounded profile 6 ply radial tyres have very low rolling resistance. Battery is lighter, chair is 100lb lighter. The stock chair claims an ISO 24miles from 56Ah Sonnenschein gel batteries. Which is bull but... With better tyres, less weight and a true 120Ah I should go at least 3x to 3.5x further. That's 75 to 85 or more ISO miles. Or real world about about 2/3rds that. We will see -- I am fat!!!

I actually look at this connector... when I salvaged my generic China pack... was it 2+ years ago? Since I had already made up the Anderson output to the TravelScoot, I just reversed it as the main charge leads... However, building a pack that doesn't get disconnected with every use, a single connector is so much cleaner. What is the service life of the connector? Is there a rule of thumb for getting the best balance reading?

Service life? Unknown. But I can soon fit another. Looks pretty well made.

Its quite heavy gold plated. But even when that's worn away I don't see much of a problem. If there is it will show on the graph screen as uneven balance? But its proportional, and so will adjust for resistance changes on the fly... Cells all look pretty well matched here to the 0.001V level! (This Shirley, is why we don't use a BMS!)

More pics while it was in the kitchen... Bit of space.BIG ONES!Just ordered anti tip wheels (80mm black hard urethane inline skate wheels) and spacers, and bearings. And a 120mm M16 8.8grade bolt for the tie down. Those have to be fitted, tested for fit and angle befopre battery can be added as I cant get it up on the bed afterwards. Too heavy!

Once the tie down bolt is in and the correct length, anti tips on, and battery in place then its all over. Just bolt the seat together. And then make a footplate (by a beermat drawing and a online laser cutter!) and drill a few holes etc to fit it. Then we can go for a silly mileage marathon!

At a narrow 24.6 inches wide its the same width as most 55Ah 22nf battery INDOOR/outdoor type chairs that use skinny tubed or rock hard flat free tyres with about 15 miles max battery destroying range like the Smaller TDX chairs, the Pride Quantum 600 and Edge chairs etc. Only with about 60 miles or 4x the range. And the ability to work properly outdoors without filling loss or the casters sinking in or high centering. Its also shorter.